Self-retracting hook mechanism



June 14, 1960 c. J. BENsoNHE-rAL '2,940,793'

SELF-RETRACTING HOOK MECHANISM Original Filed June 30, 1952 4 Shasta-Sheet 1 June 14, 1960 cvJ. aENsoN E1' AL 2,940,793

SELF-RETRACTING HOOK MECHANISM Original Filed June 30, 1952 4 Sheets-Sheet 2 Z NVENTORJ June 14, 1960 c. J. BENSON :TAL 2&940'793 sELF-RETRACTING HOOK MCHANISM Original Filed June 30, 1952 4 Sheets-She'ot 3 June 14, 1960 c: J. BENscN ETAL 2,940,793

sELF-RBTRACTING Hoox MECHANISM 4 sheets-sneu 4 Original Filed June 30, 1952 @y U4/aaa i? 5 0,924 fase l ai ,9.7 ,e4/Ey United States Patent Oiice 2,940,793 Patented June 14, 1960 2,940,793 SELF-RETRACTING HGQK MECHANISM Original application June 30, 1,952, Ser. No. 296,513,

now Patent No. 2,830,841, dated Apr. 15, 1958. Divided and this application Mar. 5, 1958, Ser. No.

1 Claim. (Cl. 294-83) (Granted under Title 3'5, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to new and useful improvements in a releasing device,and more particularlyto improvements in self-retracting hook mechanism. After an object has been ejected from a forward hook mechanism mounted on supporting structure such as an airplane, the attaching mechanism of the invention is automatically retracted within the supporting structure so that the Vexternal surface of said supporting structure becomes free of any ,of the attaching members. This is a division of my Patent No. 2,830,841 issued April l5, 1958 for 'Self- Retracting Hook Mechanism. The present invention is designed to be used in conjunction with a hook mechanism of the type that retains the shackle, thereby preventing the stores from moving out of either hook.

Previously, external stores such as bombs, gas tanks, rescue equipment, jato (jet-assist-take-od) bottles, etc., were attached to airplanes by means of fixed hook structures or retractable hooks that were articulated. The fixed hooks did not retract to form a iiush surface with the airplane when their intended purpose had been fulfilled. These projections were not objectionable when the aircraft travelled at relatively slow speed. However, with the advent of high-speed aircraft, airow becomes critical, and any projection that interferes with the smooth ilow of air over the surface of an object such as an airfoil passing through the air causes an additional drag that reduces the aerodynamic eiciency. The retractable hooks that are articulated are not flexible enough to permit installation of present external stores having variable distances between suspension lugs. Moreover, the articulated hooks require actuation linkage ties to the forward hook, and as such are not adaptable to variable suspension lug systems.

With this in mind, the principal object of this invention is to provide a rear hook releasing device that retracts within or ush with its supporting surface so that all projecting arms of said device are withdrawn within or ilush with its supporting area immediately after the attached object is released and ejected from its forward fastening and said device.

Another object is to provide a mechanism that will automatically retract the hook by the act of sliding an object out of the hook throat.

A further object of the invention is to provide a hook that will assume a retracted position Hush with the aerodynamic contour of the airplane.

A still further object of the invention is to provide a mechanism that will remain in extended position when attaching a load.

A still further object of the invention is to provide a device that is compact and small in size to enable easy installation and removal `for maintenance purposes, and

These and other objects of the invention and the various features and details of construction and operation thereof are hereinafter more fully set forth and described with reference to the accompanying drawings, in which like numbers refer to like parts.

Fig. 1 is a side-elevational view of an embodiment of the invention, the mechanism being in the retracted position.

Fig. 2 is aside-elevational view of the mechanism of Fig. l, showing the action between the crescent-shaped latch and cam plate as the hook is rotated into extended position.

Fig. 3 is a side-elevational lview of -the same mechanism with the load-supporting means in extended position prior to locking.

Fig. 4 is a side-elevational view of the mechanism with the load-supporting means in the locked extended position prior to loading.

Fig. 5 is a side-elevational view of the mechanism in the extended position with a load attached.

Fig. 6 is a side-elevational View of the mechanism after release of the load.

Fig. 7 is a sectional view of the mechanism taken along line 7 7 of Fig. 3, with the load-supporting means in extended position prior to locking.

Fig. 8 is a perspective View of the mechanism assembly.

Figs. 9a, 9b and 9c form an exploded view of the loadsupporting means, working lever and crescent-shaped latch elements.

Similar numerals refer to similar parts throughout the several views.

The self-retracting mechanism will best be understood by referring to Figs. l through Fig. 9c inclusive. 'Ihis device consists of four major elements mounted on a frame assembly, namely, a load supporting means or hook 87 rotatable on a shaft 89, a crescent-shaped latch 91 rotatable on a pin 93 of said load-supporting means, a lever 95 rotatable on said shaft, and a cam plate 85 having joining arcuate cam surfaces 109 and 111. Two springs 97 are connected at one end to a .pin 99 of said latch and anchored at the other end to a pin 101 mounted on said frame assembly. Said frame assembly is composed of a center cam plate 85 between two spacer plates 83, all riveted between two side plates 81. A thin metal case or housing, not shown, is designed to retain said mechanism. (See Figs. 8, 9a, 9b and 9c.)

In Fig. l, the mechanism is shown in the retracted position. Said load-supporting means is retained in the retracted position by the action latch 91 mounted on pin 93 of the load-supporting means. Said mechanism can be extended by pressing a screw-driver inward against one end of said lever 95. This act extends said lever an amount suiiicient to be grasped and rotated counterclockwise about said shaft 89. (See Fig. 2.) Said rotation causes said lever to bear against the toe 105 of said latch and rotate both latch and load-supporting means counterclockwise. As the latch is rotated, the cani surface of said latch cams against the cam surface 111 of said cam plate until the lever is rotated to the position shown in Fig. 4.

Continued rotation of said lever forces said latch to be rotated to a position where its camming surface 171 cams against camming surface :109 of said cam plate. At the same time, the toe 105 of said latch engages a heel notch 107 of said lever, thereby locking said loadsupporting means in the ready position. (See Fig. 4.) (It can be seen that rotation of said load-supporting means to extended position is limited by said spacer plates 83.)

The mechanism is loaded by insertingthe rear lug of the store in the throat of said load-supporting means.

Y A l Y Y Said lug bears against the tip 103 of the latch 91 and forces both saidlatch and lever to rotate, the formerin a 'connterclockwise direction and the latter in a clockwise direction.` lThis ,actionrdisengages Vtoe 105 '.fromheelY notchllll i The cam surface 117 bcams Yagainst cam surface109. (See Fig. 5.) VSaidrnechanisrnwill remain in the extended positionjas'long as said lug store is in the throat ofrsaid'load-suPPDrting means. Y

As the forward hookrmechanism releases the store and the store moves aft, either Yunder the action of air loads or positive ejection by the forward hook, said lug movesout of the tnroat of said'load-supporting means, enabling springs97 to pull said latch away from the cam surface`1i9V off cam rplate 85 to the position indicated in Fig. ,6. Continued rotation of said latch due to the influence of said springs causes the load-supporting means to rotate into retracted position flush with the `contour ofthe airplane. A spacer "block 11'3 mountedron the throat end of said load-supporting means limits the rotation of thev lever in the retracted position. Y

From the foregoing description and "llustration of the present invention it is apparent Vthat a self-releasing mechanism of simple design is,provided.'The rear vlug or shackle of a'load can be installed quickly and easily, and, when positive ejection of the load is accomplished by a forward ejecting device, said mechanism will automatically retract to a position ushgwith the contour of the airplane.V Y

The invention is nottobe construed as1limite`d to the particular rear .location described herein, .since this is regarded to be illustrative rather .than restrictiva "For" example, thedevice can be located forward of the ejecting type hook mechanism, said relative location being 4 Y determined by the suspension system to be used, or installed to suit any/'suspension lug configuration desired.

We claim: l

A self-retractingV device comprising a frame assembly including a pin, a cam platehaving joining arcuate cam surfaces with their centers in'spaced relation, a shaft substantially concentric with vone of said 'centersY and spaced from the other center, load-supporting means mounted on said shaft, saidload-supporting means iinl cluding Ya hook rotatable into extended rand :retracted positions, a crescent-shaped latch`having a toe and tip pivotally mounted on said load-supporting means for rotation into holding position with said toe locking against one of saidcam surfaces and into-releasingposition with the ecrescent convex surface slidably engaging the other cam surface, said crescentv latch having its tip end adaptd to be extended intothe hook andhaving a pin projecting therefrom, a lever rotatably mounted on said shaft and having a 1 notch engageable by said `toe ,of .the `crescentshaped latch in holding position, a spring attached to said pin of said crescent`latch and to l-said pin ofsaid frame assembly, Vsaid spring urging said crescent latch, "said load-supporting means and saidleverinto retractedposition, and mating cam surfaces on -said Vcrescent-shapedlatch .and said-'lever for cooperation in the transition from retracted position to extended position.

References Citedin thevle of this patent UNITED STATES PATENTS Y 

